Density of Silicone Rubber: The Key Calculation

Silicone rubbers used for casting moulds typically have a density between 1.05 and 1.20 grams per cubic centimetre (g/cm³). To convert 7 litres (7,000 cm³) into kilograms, multiply the liquid volume by the product’s density:

For example, with a typical silicone density of 1.10 g/cm³:
7,000 cm³ × 1.10 g/cm³ = 7,700 grams = 7.7 kilograms.

Precision Matters: Avoid Overbuying or Shortages – Always round up to allow for mixing loss, spillage, and any additional coverage required for complex mould shapes. Buying a little extra silicone prevents mid-project interruptions.

Converting Silicone Volume to Weight

To calculate kilograms from litres, multiply your total litres by the density of your chosen silicone rubber (kg/litre). For most casting silicones, plan for a density around 1.10 to 1.15 kg/litre. Example: 7 litres x 1.10 = 7.7 kg. Always check the individual product’s datasheet to confirm density.

“Liquid Mould” – Casting Liquid Silicone Rubber, 15 Shores 20.8 kg

The “Liquid Mould” – Casting Liquid Silicone Rubber, 15 Shores 20.8 kg is designed for high precision and versatile applications. This bi-component A + B silicone is excellent for reproducing even the finest details due to its superior flow and high mechanical characteristics. Ideal for casting detailed moulds for small objects, jewellery, technical pieces, and artistic reproductions, it is compatible with resin, soap, polymer pastes, and natural or synthetic waxes.

Provided in 20.8 kg kits, it allows users to efficiently tackle large volume casts, such as your 7-litre pour. Ensure to mix both components thoroughly prior to use, and remember to allow for a small margin during calculation.

“Liquid Mould” – Casting Liquid Silicone Rubber, 5-40 Shores, Bi-Component A+B

If you require more flexibility in shore hardness, the “Liquid Mould” – Casting Liquid Silicone Rubber, 5-40 Shores, Bi-Component A+B gives you a wide range of hardness options in a traditional bi-component format. This makes it suitable for small to medium projects and multiple reproductions. Ensure you add the required catalyst (activator) before pouring, then mix as per the manufacturer’s recommendations for best results.

“Pure Mould” – Translucent Liquid Silicone Rubber for Mould Making

The “Pure Mould” – Translucent Liquid Silicone Rubber for Mould Making is a platinum-based, fast-hardening option with a simple 1:1 mix ratio. Its translucency allows you to perfectly control and monitor your mould during setting. This product minimises shrinkage and supports multiple use cycles, making it an excellent choice for creatives needing precise moulds with prolonged durability.

Tips for Accurately Measuring and Mixing Silicone Rubber

The most reliable way to ensure you have the right amount is to calculate volume first and convert to weight using the stated density (from the technical datasheet or product instructions). Always account for a little excess – rounded up to the nearest usable pack size. The correct ratio of parts A and B is critical; blend until fully homogenous to avoid weak spots in your final mould.

Check product technical datasheets for exact densities before purchase, since brands and silicone types may vary slightly.

Storing and Handling Silicone Rubber

Mix thoroughly for even curing. Seal unused portions in airtight containers to prevent premature curing or contamination. View all products in the Silicon Rubbers category here.

Store unused silicone in airtight containers away from direct sunlight and moisture to keep it fresh for future use.